Without limiting the scope of the invention, its background is described in connection with treating liquids in particular drinking water, wastewater, beverages, juices, milk, emulsions, ballast water, bilge water, cooling tower water, process water, mill water, raw sewage, crude oil, hydrocarbon streams, black liquor and any pumpable liquid, as an example. There are various liquid streams that must be treated or processed in order to meet quality control standards or discharge permit requirements. For example, drinking water may be considered a product that must meet strict treatment requirements such as disinfection in order to render the water safe for human consumption. Likewise, there are other contaminants which may affect the quality of the water, such as iron, arsenic, hydrogen sulfide, organics and turbidity.
Once the drinking water leaves the faucet at a residential location it is now referred to as wastewater. Wastewater must also be treated in order to remove contaminants prior to discharge. One treatment method that is rapidly gaining in popularity is the use of UV radiation for disinfecting wastewater. Likewise, it is also being used for disinfecting drinking water. Another application that is being used in combination with UV radiation is the addition of an oxidant such as hydrogen peroxide or ozone in order to form hydroxyl radicals.
There are several major water streams that have gained widespread attention within the past few years. First, when left untreated, combined sewer overflows (CSO) and stormwater affect receiving streams. During heavy rainfall the shear volume of stormwater that must be treated has challenged engineers, scientists and municipalities. Two pollutants commonly found in CSO and stormwater runoff are floatables and pathogens. The US EPA, municipalities, scientists and engineers are currently searching for an extremely rugged CSO and stormwater treatment system that can both filter and disinfect prior to discharge to receiving streams.
Another water discharge that has challenged the marine water treatment industry is water discharged during ballasting operations for large ships. The problem with ballast water is that it may carry non-indigenous species that when discharged into a new environment can literally overwhelm and eradicate other lifeforms within that ecosystem. Thus, ballast water must now be disinfected prior to release. Likewise, ballast water may contain oil and grease residuals which must be removed prior to discharge.
Hydrocarbon contaminants, especially water soluble organics (WSO) have plagued another industry that operates in a marine environment. Offshore Oil and gas production platforms produce copious amounts of water along with the oil and gas. The produced water often contains WSO which must be removed from the water prior discharge. Although mechanical separators, such as hydrocyclones, can remove the insoluble hydrocarbon fraction, the soluble organics require extensive as well as expensive treatment methods such as acid extraction.
At land production wells, another contaminant, salt must be removed via evaporation or reverse osmosis prior to discharge or must be disposed via deep well injection. Likewise, when a well is drilled and then fractured, the flowback water must be treated prior to discharge.
Typically, most municipal water treatment facilities, both drinking water and wastewater incorporate some form of oxidation. This may be in the form of biological oxidation or addition of an oxidant such as chlorine, bleach or ozone. Many industrial wastewater streams have a very high chemical oxidation demand (COD). Thus, the water must be pretreated prior to discharge to a biological oxidation wastewater treatment plant.
One such industrial process stream is spent caustic produced from ethylene plants. Another oxidation process, wet air oxidation, is commonly used to oxidize the organics within spent caustic. Wet air oxidation consists of adding oxygen to the stream then heating and pressurizing the stream in order to oxidize the containments. Due to the high pressures and temperatures coupled with the addition of oxygen, exotic metals must be used in order to prevent corrosion, another form of oxidation.
Two other streams found in another industry, the pulp and paper industry, must be oxidized prior to use. First, pulp is oxidized to remove color. The pulping liquors must be oxidized in order to recover the valuable chemicals. However, the black liquor must be evaporated to remove access water that will not support combustion or oxidation of the black liquor. Likewise, the pulp must be separated and filtered in order to remove fines.
A common mechanical separator used in pulp and paper mills, on drilling rigs, in the mining industry and the oil, gas and oilsands industry is the hydrocyclone. Hydrocyclone separators are commonly used for phase separation purposes. Particles or fluids with a different density than water or the bulk liquid can be separated utilizing centripal force by means of a hydrocyclone. Hence, if the fluid is a liquid, a cyclone separator is typically referred to as a hydrocyclone, regardless if the bulk liquid is water, crude oil, gasoline, drilling fluid or any other liquid. And if the bulk fluid is a gas, then it is commonly referred to as a cyclone separator.
Hydrocyclones are normally classified according to flow direction. For example, referring to prior art hydrocyclones as shown in FIG. 13, a forward flow hydrocyclone A discharges the accepts 1302 in the same axial direction as the bulk flow. The rejects 1304 are reversed and exit opposite of the bulk flow direction. Reverse Flow Hydrocyclones B discharges the accepts 1302 via a vortex finder and must reverse its axial direction with respect to initial bulk flow. A Throughflow Hydrocyclone C discharges both its accepts 1302 and rejects 1304 in the same axial direction of the bulk liquid flow. In all three hydrocyclones the whirl, swirl or vortex flow direction remains unchanged with respect to the initial rotation imparted on the fluid via the volute—clockwise or counterclockwise.
It is well known and well understood that the hydrocyclone forms a gas core in the center if open to atmosphere or a gas is injected into the hydrocyclone. The gas seeks the center of the hydrocyclone, since air or gases are less dense than water. Likewise, solids and liquids that are more dense than water will be forced outward and ejected through the apex valve and thus can be separated from the bulk liquid. Also, the less dense gas and water are ejected and discharged through the vortex finder.
All of the aforementioned liquids, in one manner or another, are treated with both separation and oxidation. For example, if oxidation will occur at elevated temperatures, such as wet air oxidation, the liquid must be preheated in order to start the reaction between dissolved oxygen and organics. The furnace tube used in wet air oxidation systems is very costly and transfers heat via conduction—through the wall of the pipe. For wet air oxidation to become a mainstream treatment technology another form of heating must be used in order to reduce both the operating costs as well as capital expense.